What is the efficacy of mammographic screening for breast cancer detection?

From the Guidelines

Mammographic screening is effective in reducing breast cancer mortality by at least 22% and should be performed annually in women aged 40-84 years, as it decreases treatment morbidity and improves quality of life. The most recent and highest quality study, published in 2024 in the Journal of the American College of Radiology 1, demonstrates that mammography screening reduces breast cancer mortality, with a 27-31% reduction in mortality observed in the Swedish Two-County trial.

Key Points

• Mammography screening should be performed annually in women aged 40-84 years, as it decreases treatment morbidity and improves quality of life 1.
• Women should continue screening as long as they remain in overall good health and are willing to undergo the examination and subsequent testing or biopsy, if an abnormality is identified 1.
• The benefits of mammography screening, including reduced breast cancer mortality and improved treatment outcomes, outweigh the risks, such as false positives and overdiagnosis, for most women 1.
• Digital mammography has improved detection rates compared to film mammography, particularly in women with dense breast tissue, and supplemental screening with ultrasound or MRI may be recommended for women with dense breasts or high risk factors 1.

Screening Recommendations

• Women aged 40-49 should discuss individual risk factors with their healthcare provider to determine appropriate screening intervals 1.
• Women at high risk, such as those with a family history or genetic mutations like BRCA1/2, should begin screening earlier and have more frequent screenings 1.
• There is no upper age limit agreed upon for screening mammography, and women should continue screening as long as they remain in overall good health and have a life expectancy of 10 years or more 1.

From the Research

Efficacy of Mammographic Screening

• The efficacy of mammographic screening in reducing breast cancer mortality has been established for women aged 50 years and older, with a 34% reduction in age-adjusted mortality rate over the past 20 years 2.
• However, the benefits and harms of screening in women aged 40-49 years are still debated, with some studies showing no significant effect on breast cancer mortality 3, 4.
• A systematic review of randomized controlled trials found no significant effect on breast cancer mortality or all-cause mortality in women aged 40-49 years offered screening, but noted limitations in the studies, including low sensitivity of screening and screening attendance 3.
• Another study found a non-significant reduction in breast-cancer mortality in women invited for annual mammography from age 40 years, but estimated a 24% mortality reduction adjusted for non-compliance in women actually screened 4.
• The American College of Radiology recommends annual screening beginning at age 40 for women of average risk, and earlier and/or more intensive screening for women at higher-than-average risk 5.

Benefits and Harms of Screening

• The benefits of screening include early detection and reduced breast cancer mortality, but also include harms such as false-positive recalls and over-diagnosis of invasive breast cancer 3, 4.
• The cumulative risk of experiencing a false-positive recall was estimated to be 20.5% in women aged 40-49 years offered screening, and over-diagnosis of invasive breast cancer at 5 years post-cessation of screening was estimated to be 32% 3.
• The risks and benefits of screening should be individualized for each patient, taking into account their personal risk factors and medical history 6.

Screening Recommendations

• The American College of Radiology recommends annual screening beginning at age 40 for women of average risk, and earlier and/or more intensive screening for women at higher-than-average risk 5.
• Women with genetics-based increased risk, those with a calculated lifetime risk of 20% or more, and those exposed to chest radiation at young ages are recommended to undergo MRI surveillance starting at ages 25 to 30 and annual mammography 5.
• Women diagnosed with breast cancer before age 50 or with personal histories of breast cancer and dense breasts should undergo annual supplemental breast MRI 5.